The photon statistics of the WCP signal states are described by a Poissonian distribution \(P(n)=\exp (-\mu )\mu ^n/n!\)  where \(\mu \)  is the mean number of photons per pulse. An eavesdropper can perform a photon number splitting attack on the multiphoton emissisions [1]}, [2]}. To counter this, we use the so-called decoy state method to estimate the number of received vacuum and single photon emission events [3]}, [4]}, [5]}.
